Continuous filament non-woven fabric has remarkably high strength and favorable dimensional stability as compared with short fiber non-woven fabric. Moreover, it can be produced through direct coupling with the spinning process resulting in an appreciable cost reduction.
Conventional continuous filament fabrics are coarse or rough and stiff having a paper-like appearance, because web making through direct coupling with spinning does not provide an opportunity for imparting the crimp to the constituent filaments in order to develop the desirable bulkiness. A conventional method used to provide crimping after forming the web is to preliminarily impart a latent crimp to the web through conjugate spinning or the like. However, this method does not develop sufficient bulkiness, because in a continuous filament web, the crimp tends to be overlapped in its phase and the binding force among the filaments is extremely strong.
Another method of forming the web is through simultaneously separating the filaments and imparting a crimp by causing filaments taken off at high speeds to reflect or turn with a baffle or a impinge plate. This practice is disadvantageous in that not only is sufficient crimping difficult to obtain, but the filaments are not readily separated. The consequent difficulties in making the bulkiness and the uniformity of the web compatible result in a product with inferior strength.
Furthermore, the use of polyethylene terephthalate filaments or nylon filaments in the above-described methods renders it impossible in such methods to simultaneously obtain remarkable flexibility and bulkiness.
Continuous filament non-woven fabric, therefore, has been strongly restricted thus far in the development of applications in industries and for apparel items in which high heat insulation and flexibility are required.